Automatic switch for use in telephone systems



1933- c. R. WOODLAND ET AL 1,935,927

AUTOMATIC SWITCH FOR USE IN TELEPHONE SYSTEMS Filed Dec. 24, 1931 6 Sheets-Sheet l @E 1 T H i l 7 r. :3 lg 9 in 1 1 '4 i l ifi i Z\ 5% a IT\' I" 1. g g1 I9 I 45\ i L 56 20 79 I, n 3 5 g a0 \2 I :1} I l l "h E 1 l :3

1933' c. R. WOODLAND ET AL 1,935,927

AUTOIA'IIC SWITCH FOR USE IN TELEPHONE SYSTEMS Filed Dec. 24. 1931 6 Sheets-Sheet 2 NOV. 21, c R W L ND ET AL AUTOMATIC SWITCH FOR USE IN TELEPHONE SYSTEMS Filed Dec. 24. 1931 6 Sheets-Sheet 5 1933- c. R. WOODLAND ET AL 1,935,927

AUTOMATIC SWITCH FOR USE IN TELEPHONE SYSTEMS Filed Dec. 24. 1931 6 Sheets-Sheet 4 1933- c. R. WOODLAND ET AL 1,935,927

AUTOMATIC SWITCH FOR USE IN TELEPHONE SYSTEMS Filed Dec. 24, 1931 6 SheetsSheet 5 1933- c. R. WOODLAND ET AL 1,

AUTOMATIC SWITCH FOR USE IN TELEPHONE SYSTEMS Filed Dec. 24, 1931 6 Sheets-Sheet 6 60 yerticaland rotary magnet ,armatures.

Conveniently the pin may take the form of an extended tongue on a washer-shaped member which may be secured to the end of the vertical hub by riveting it in position, while the hole in the washer which is concentric with the slightiyiess in diameter hole in the vertical operating hu'o may be made to serve as a bearing surface on the vertical guide pillar.

Considering now particularly the vertical movement mechanism, it will beseen from Fig. 3 v

that the operating magnet 22 is mounted, inside the box casting while its armature 23 which is pivoted at the point 81 is located at the front of the casting and is provided with an extended arm 24 which is bent at its end into the form of a fork so that the vertical operating pawl 25 may be pivoted therein, in which position it is readily accessible for adjustment purposes. In the views Figs. 2 and 3 the armature and pawl are shown in operative engagement with the vertical hub,

and it should. be explained that the pawl is providecl; with a spring which'may be conveniently supported onthe pivot pin, and is arranged to exertpress'ure on the pawl in such direction as to ca u sje'it to engage with the vertical hub. In

" order, however, that the. pawl shall be clear of thehub'fwhen the armature is in its normal position, it is provided with an extended arm 26 shownin Figs. 2 and 5 arranged to engage with 30, the adjustable stop 27, comprising a bolt and locking nut, which may be adjusted as regards its heightto produce the. necessary tilting movementto lift the pawl'clear of the hub when the normal position is reached. A fiu'ther adjustment for thearmature. as regards its stroke is pro'vided in the shape ofthe adjusting screw 28 shown immediately below the forked portion of the extendedfarm in Figs. 2 and 3.

Considering now theenergization of the vertical magnet22'jdu'ring' the operation of the switch,

'itfwill be appreciated from Fig. 3'that the armature on being attracted by the magnet will cause the extended arm to rise and asthe pressure on the extended arm of the pawl is by this means relieved, the latter will under spring pressure enteratooth on the verticflhub which is then liftedv carrying with it the shaft and wipers until the pawl locks against the upper pawl stop 29. The upper pawl stop 29 is also slidably adjustable lo and may belocked inpositionby means of the "bolt 30' so as to regulate the stroke of the armature and' consequently the lifting motion of the shaft and wipers. In manner, therefore, the shaft and wipers are raised upon the operation of ,.the armature which as will be seen from reference from" the front of the switch so that adjustment "may'b'e carried out without removing it from the mounting shelf.

Referring again to Fig. 1 it will be seen that the .vertical hub is provided at its lower end 7Q .with a conical shaped cam 32 arranged to cooperate with a projection on a pivoted lever 33 which .actuates the off-normal spring assembly shown more clearly in Figs. 5' and 7. In order that the action of, this lever shall be more clearly I? understood a separate perspective view has been provided in Fig. '7 from which it will be seen when the shaft is lifted the cam will clear the operating lever 33 so that this latter will then be moved by the pressure of the spring set into its operated position'against a projection on the casting in which position the contacts shown will be opened. As already mentioned the restoration of the ofi-normal spring set is performed in two stages and the manner in which this is effected will be fullydescribed later.

Vertical magnet interrupter springs may be fitted when required on the lower right-hand side of the casting in the position indicated by 34, Fig. 2, and are operated by a ball and plunger arrangement. Conveniently in the construction shown the ball 35 is' housed in a cavity formed in the casting and-is rendered captive therein by ring punching .the sides of its cavity to a slightly smaller diameter than that of the ball so that a'portion of its circumference may extend therefrom to be in line with the operating path of the vertical magnetarmature. Consequently when the armatuneisenergizedQits right;- ho.nd edge will. ride over the-surface of. the ball so as. to cause the-latter to recde into the cavity thereby operating the. plungerv 36,

which is provided at its endwith aninsulated. buffer to effect .the operationvofv the vertical magnet interrupter spring set 34.

At .each vertical step the vertical hub and-shaft are held in position by aspring-loadeddetent.

pin.37 shown hinFig. a which is slidablv, supported betwee'nthe arms of a U-shaped bracket 38 which is, in turn, secured ,to a.' smaller pro- J'ecting a Inid.position.on .the frontface of the casting. The' ,contact faceofv the' 'pin is cutfin such mannenlas .to' correspond to the angle of the ratchetteeth ontheverticah hub and in order that' its.',move rnnt'sliall be restricted within the ,desired '.,.'a..further. guide. pin 39 is set trahsversely througli .the. he;

which. rides inla. slot; cirt, U-shaped supporting member.

in, the;possu :.ifndi Q tar.big ga -ind {glimljigi a and e e te it-se ara e l i ac ii fr m,-

tent piiti and is providedwithiaj leirtndedend the 'b'ase '0: pie;

Conveniently also the. guide pih is 'arrangedto holdiin position 2.

plate for,

ings are v a ring came! mounted -on the verticalhiib. I The.

mounting of .thelevers; designated 45 shownmore 2 -a ndl fi which it will be seen that -they are pivoted one behind the. otherto anext'ende'd bracket secured -to .the

' casting. and. are provided faces equal in'LlengthI'to ,the vemtngmova.

ment of the switch 'mtbj' anpr. these J Operating e s e ed L we. -.-l .19 5 int which operating, studssuch as. '1 4i; may

be secured in positions 'de'pending upo n't he levelor..levels.at which it is.desired. .ta,efiect. operation of 'the sprite sets. .The operating. cam is shown more. clearly in Fig. 1 from. which-it will be apprciated-asthe. shaft is lifted. the-ring will engage with.'the" studs. in the. desired posi tions and effect a rocking. movement of the levers to operate the-spring sets. .In order.to:. reduce friction when the-.shaftis subsequently rotatedit is arrangedthat the operatingring 44 is mounted loose on,.the shaft so that-it is free to rotate independently.

The rotary stepping of the shaft is carried out-by a single coil and magnetsimilar to that used for the vertical 1 steppingwhich is also mounted inside the box casting above the vertical magnet in the position indicated by 49 in Fig. 6. Both magnets are secured in position by clamping screws which extend through slotted holes in the casting and these may be seen more clearly in respect of the vertical magnet mounting shown in Fig. 5 in which fixing screws are designated 50 and 51. Moreover the magnet fixing bracket 52 is arranged'to slide between'ribs provided on the inside face of the casting, so that when it becomes necessary to alter the position of the magnet this may be done by slackening off the screws 50 and 51 so that the magnet assembly may slide backwardly or forwardly between the ribs. In order to permit of a comparatively fine adjustment the movement is controlled by a screw similar to the screw 53 shown more clearly in Figs. 2 and 6 associated with the rotary magnet 49. This screw is threaded into the casting and provided with a collar 54' which enters into a slot in the magnet fixing bracket so that when the screw is rotated in either direction a corresponding backwards or forwards movement of the magnet will be secured.

Considering now the rotary magnet mechanism shown more clearly in Fig. 6 it will be seen that the operating magnet is provided with an armature 55 also located on the front of the switch which is pivoted at the point 82 and provided with an extended arm 56 carrying a spring-loaded pawl 5'7 normally arranged to bear against the ratchet teeth 9 which as previously explained are provided in a complete circle around the flange on the cylindrical hub. In the drawings the rotary magnet armature and pawl are shown in their operated position, so that when the magnet is de-energized the armature will restore under pressure of the flat restoring spring 31 and carry with it the rotary hub until the pawl takes up the position indicated by the dotted lines when it becomes locked against the adjustable pawl stop 58. A light holding detent spring 59 which is also adjustable from the front of the switch is incorporated in the rotary mechanism so as to prevent the movement of the shaft in a reverse direction as the pawl 5'7 is being drawn over the ratchet teeth 9 into its operated position by the energization of the magnet 49. The pawl stop 58 may be slidably adjusted and locked in position by the locking screw 60. In addition to the pawl stop an adjustable armature stop 61 is provided shown more clearly in Fig. 3 and this comprises a bracket carrying a projecting tongue which is secured to the edge of the casting flange 11 through slotted holes so that it may be adjustable as regards its position, and is arranged to contact with the turned up end of the armature lever 62 so as to regulate the releasing stroke.

Since with the present construction the usual shaft cup'spring has been dispensed with, it is found that the power to operate the shaft is reduced to approximately one half and it is anticipated that this saving combined with the reverse stepping rotary movement will enable a hunting speed comparable with that of a single motion switch to be obtained. At the conclusion of each rotary step the shaft is held in position by the detent pawl spring 59 and as the rotary detent is quite separate and distinct from the vertical detent it is not now necessary to enlarge the size of the vertical ratchet teeth at the point where they contact with the detent pin during the vertical movement. This enlargement of the ratchet teeth has hitherto been considered essential to ensure the reliable operation of the sci-called double dog detent during the rotary movement.

Rotary magnet interrupter springs may also be fitted if required to the left-hand side of the switch frame in the position indicated by 63 in Fig. 2 and these may be operated by an extended arm 64 on the rotary magnet armature in the manner shown in Fig. 6. Conveniently in the construction shown the rotary interrupter spring assembly is arranged to open contact at the conclusion of the attraction stroke, and in order that the magnet may be reliably energized in a selfinterrupted circuit without the possibility of the mechanism failing to function owing to clipped impulses, a certain degree of lost motion is incorporated in the operating mechanism. As will be better appreciated from Fig. 6, this mechanism comprises essentially an'insulated buffer 65 slidably mounted to a pin 66 which is riveted into-the end of the operating lever, shown in Fig. 6 in its operated position. In the normal position when the magnet is de-energized the buffer is inserted between the spring sets shown so that their turned up ends will drop into the recessed portion on the buffer to allow the electrical contacts 67 to make. On the operation of the magnet the armature will be well advanced in its stroke before the buffer is withdrawn from between the springs into the position shown, since the pin on which it is mounted is of somewhat greater length than the buffer, and will not, therefore, impart the movement to the buffer for an appreciable period after the initial movement of the armature. Similarly upon the de-energization of the magnet the switch shaft will be well advanced in itsoperating movement before the buffer is again inserted between the spring set to close the electrical contacts. In this manner, therefore, the energizing circuit of the magnet is controlled by the movement of its own armature which incorporates a double-acting delay device to ensure that each movement of operation and release shall be adequately made before the circuit change which terminates the movement is again effected. Alternatively in case the magnet is to be controlled in a circuit which does not necessitate this delayed action device, the interrupter springs maybe operated without lost motion by an extension of the rotary magnet armature or alternatively by a ball and plunger arrangement similar to that described in connection with the vertical magnet interrupter springs.

Rotary oiLnormal springs are also secured to the left-hand side of the casting at the point designated 68 in Fig. 2. These springs are normaily held operated under strain by a projection 69 screwed or moulded on to the cylindrical face of the rotary hub which engages with the spring mounted cranked operating lever 70. As soon as the hub commences its rotary movement the projection will be moved out of line with the operating lever and the spring sets are then operated under tension of their own moving springs, or alternatively by means of a special spring which could be conveniently incorporated in the same assembly.

As already mentioned the release of the switch is effected by rotating the shaft and wipers clear of the banks whereupon they fall by gravity and are then moved to the normal position in a manner which will now be described. When the shaft is rotated into its 11th position, so-called cam springs designated '71 shown to the right- I hand side of the switch casting in Fig. 2 are operated by a further projection 83 on the cylindrical' portiotfof the rotary hub, but their operation is without function at this stage since the circuit-conditions ruling at the time are indicative of a release condition rather than an 5 all-outlets-busy condition and the necessary distinction between the two will be readily conceivable to those skilled in;,the art WlthOllt further description herein. Further rotation of the shaft into the 12th position will efiect the operation of further cam springs designated 72 in Fig. 2 and these are arranged to disconnect the rotary magnet circuit. In this wipers will be moved clear of'the bankcontacts and a still further projection 84 on the'cylindrical hub more'clearly seen in Fig. 2 will engage with the guide pin 39 of zthe,=vertical detent 37 thereby 'movingthej, latter against the tension of the spring 41' out of engagementwith thev vertical ratchet teethso that the 'sha-ftand wipers fallby gravity into, their vertical normal posi: tion. In this positionthe conical shaped cam 32 at the base of the vertical hub shown in greater detail in;Flg. 7 effects the operation of a single set of off-normal springs 73 but does not effect the remainder ofthe spring assembly since the end of the leverenters the recessed portion 85 of the cam and therefore only a slight movement is'produced. The operation of the light off-normal springs .73 again connects up the rotarymagnet circuit so that the shaft and wipers are moved ayfurther two rotary steps into their final home position, and by this means the operating lever 33 .will be caused to ride out of the recessed portion of the cam on to the external face and this latter movement serves to effect the full operation of ,the off-normal spring sets. In this manner a large assembly of off-normal springs may be reliablyoperated irrespective of the weight of the shaft since the major restoring movement is produced from the. rotary magnet drive.

The cordless wiper. arrangement may be more clearly seenlin the plan view, Fig. 4, and comprisesthe usual wiper. arm 74-together with an arc shaped wiper brush 75 both .of which may be convenientlypressed out ina single stamping. A contact comb .86 is also provided and is secured to the square sectioned pillar 76 fastened to the base flange of the switch casting. As will be 568 seen from-Fig. 2 the contact comb is provided with' terminal points such as-Z'lequal in number to the contact levels and arranged so that-the upper and lower are shaped brushes may establish continuous contact with them during the rot-ation of the wipers to any set of contacts in the associated level. In the particular example shown it is assumed that the switch is to be used in circumstances where not more than 10 outlets are required for a singlerotation of the shaft tmd wipers and under these conditions it is necessary to provide double-ended wipers and also double feed brushes. In case, however, 20 outlets are'required for a single rotation of' the GM switch, single-ended. wipers will banks successively, so that as one wiper leaves the upper bank the lower wiper will enter the lower bank and in this manner 20 consecutive 3 outlet points are provided for a single rotation of the shaft and wipers. In connection with the wiper and comb arrangement it may be pointed out that thecontact arc and the actual wiper arm.-need not'beadjnsted relativeto each other fiesinga with the arrangements contemplated'the' position the be used; arranged to contact with upper and lower wiper arm 74 will notice required to pass over the comb 'feeds'86 for the contact are 75.

Considering this feature in detail, whenvthe wipers arerotatedinto their 12th position they wiper armwill leave the contact bank while at the same instant the contact are will leave the comb feed; Consequently when the mechanical.

release action comes into operation the shaft andwiper will drop clear ofboth the comb and the contact, and when the home position is reached'the light off-normal springs will be .operatedto close the rotarymagnet'circuit by means of which two further. steps will be taken to advance the wipers into their rotary home position;

Since; however, the shaft and wipers are fully.

restored insofar asqthevertical release movementisconcerned'during their final rotary steppingsoperation it willbe clear that the wiper arms will move into their normal position'well.

below the comb feed. This feature is of importance. since otherwise if the-arrangements were such that the wiper arm was caused .to .wipe

over the cornbv feeds during each'revolution, then very careful aligning would be. necessary between the. comb. feed and the bank contacts so as to ensure that there should be no possibility of the wiper arm fouling the'comb during the release operation. It may be mentioned that the elimination of the wiper. cord makes possible a saving in the overall height of the switch since it is not now necessary to provide clearance space below the banks for the usual cord loop.

Although not shown in the drawings provision is contemplated of a semi-circular guard plate arranged to be fastened in front of the banks and wipers so as to protect them from damage. Convenientlyinone construction thisguard may take the form of a metal plate punched'out with a very coarse mesh so as to permitminor adjustment to be made therethrough, but at the same time providing adequate protection against accidental damage.

A vertical bankand wiper may also be fitted t0 the switch on one of the-bank mounting pillars as is the general practice at the present time, while a so-called P. B. X. ban-k arc may be fitted immediately below the normal ban-k assembly on the same mounting pillars.

Since the switch is now mechanically capable of testing 20 contact pointsconsecutively, the use of the so-called double choice relay-generally employedin circuits for switches having more than 10 outlets may now bedispensed. with,.. thereby considerably simplifyingthe circuit arrangements and necessitatingno change in the size of the relay mounting plate. In this connection consideringa group selector switch of the well-known construction which requires only four control relays, there is a. saving of approximately four inches inthe. overall-height of the'switch and a further saving of approximately one' inch from back to front.

The-use of a separate base plate and felt ring for-the prevention of dust trouble is now discontinued and replacedby-the flange 12 shown infFig. 1 which is; formed with the casting and provided with a turned over lip all round. The

dust cover 78 is ofconventional form and is now arranged'to fit flush against the sides of the lip formed around the base flange thus obviating trouble-which has been experienced.- hitherto owing to-particles of felt fluff produced by the continuous useof the cover becoming lodged between the operating contacts thus preventing the proper functioning of the switch. In order to follow the general practice of insulating the switch mechanism from the mounting plate and shelf, an insulated beading of generous dimensions is provided around the lower edge of the dust cover at the points where it overlaps the base flange. Conveniently this beading may take the form of a U-shaped strip of insulating material '79 clamped in position by a U-shaped strip of metal of similar dimensions. At the point where the cover contacts with the top of the mounting plate a resilient strip 8'7 will be provided composed of material which is not productive of fluff during use.

We claim:

1. In a switch structure, two wiper sets, means for moving the wiper sets in two directions to associate one set with a cooperative set of fixed contacts, apparatus enabling a part of said means to further move said wiper sets to enable their partial restoration, and means operated consequent to such partial restoration enabling the said part of said means to further move said wiper sets to position the other of said wiper sets in the same relation to the fixed contacts as was the one set prior to the operation of the switch.

2. In a switch mechanism, a shaft, means for elevating said shaft, means for holding said shaft in its elevated position; means for then rotating said shaft variable distances to selectively establish electrical connections; means operated to disable said second means consequent to the subsequent rotations of said shaft an additional distance thereby causing said shaft to drop to its initial level, and means operated consequent to the restoration of said shaft to its initial level to enable said third means to again rotate said shaft an additional distance making the total distance of rotation 180 for each operation and release of the switch.

3. In a switch structure wherein a wiper set is first moved in a primary direction to select one of a plurality of groups fixed contacts and is then moved in a secondary direction to establish a connection with a particular contact of the selected group; the provision of means enabling only a partial restoration of said wiper set to be required to enable the switch to again perform its specified selecting and connecting function.

4. In a switch structure wherein a wiper set is first moved in a primary direction to select one of a plurality of groups of fixed contacts and is then moved in a secondary direction to establish a connection with a particular contact of the selected group; and wherein the restoration in the primary direction is effected as a result of a continuation of the secondary movement; the provision of means enabling the restoration to normal to be brought about by still further secondary movements of the wipers.

5. In a switch mechanism, a supporting member, a shaft having a bearing in said member, means for transmitting endwise movement to said shaft, sets of contact springs arranged on said member, and a plurality of arms pivotally mounted on said member actuated by said shaft during its endwise movement to operate said sets of contact springs.

6. In a switch mechanism of the type in which a set of wipers is caused to move in a primary direction to select one of a number of contact groups and which is then moved in a secondary direction to connect with a set of contacts of the group selected; mechanism which causes the wipers to move clear of their contacts and restore as regards their primary position; and other mechanism operative, consequent to the specified restoration, to effect the further movement of the wipers in the secondary direction to complete the restoration of the switch.

7. In a switch mechanism wherein a shaft is operated in a primary direction and then in a secondary direction to position its wipers into,

electrical connection with a specified set of bank contacts; means for initiating and completing the restoration of the switch to normal by subsequent operations of the shaft in a secondary direction.

8. In a switch mechanism wherein a shaft is operated in a primary direction and then in a secondary direction to position its wipers into electrical connection with a specified set of bank contacts; means for holding the shaft against a restoring force tending to move the shaft to normal with respect to its primary movement, means operated consequent to a continued secondary movement to disable said holding means, means operated upon the consequent restoration of the shaft to effect a further limited secondary movement thereof to fully restore the shaft to normal position with respect to both movements.

9. In a switch mechanism wherein a shaft is operated in a primary direction and then in a secondary direction to position its wipers into electrical connection with a specified set of bank contacts; mechanism for restoring the shaft to normal by a further movement thereof in a secondary direction to effect the restoration thereof as regards its primary movement, and means actuated upon such restoration to. bring about a further movement of the shaftin a secondary direction to restore the shaft to normal as regards its secondary movement.

10. In a switch mechanism of the character covered by claim 9, characterized in this; that all springs of a set of off normal springs are arranged to be fully operated upon the initial primary movement of the shaft, some of which are restored upon restoration of the shaft as regards its primary movement, and the remainder of which are arranged to be restored upon a completion of the last specified secondary movement.

11. In a switch mechanism, a base having mounted on one side thereof a plurality of relays having circuit controlling springs, the terminal portions of the springs passing through openings in said base, a member also mounted on said base comprising a switch mechanism; and a plurality of circuit controlling springs forming a part of said switch mechanism proper, said springs having their terminal portions passing through openings in said base, thereby enabling all wiring in the various springs of the switch mechanism as well as of the relays to be made on the side of the base opposite to that on which said relays and switch mechanism are mounted.

12. In a switch mechanism wherein a shaft is operated in a primary direction and then in a secondary direction, a set of wipers carried by the shaft having a flat sector-shaped plate integral therewith, and a fixed comb-shaped member to which external connections are made and the teeth of which are adapted to be engaged by said plate.

13. In a switch mechanism wherein a shaft is operated in a primary direction and then in a secondary direction, means for effecting the primary and secondary movements of the shaft comoperated in a primary direction and then in a secondary direction, electromagnets having armatures for operating such mechanism, a pair of interrupter contacts, and 10st motion means actuated by one of said magnets to open said contacts at one end of its armature stroke and to again close said contacts at the other end of its stroke.

CECIL ROBERT WOODLAND. JOHN HENRY ELLIS. 

